Research locates cold-water areas crucial for fish survival

Methow Valley News

To humans, rivers in the Methow can seem pretty frigid, even in August. But for fish in the Methow, having cold water – really cold – is a matter of life and death.

Aquatic ecologist John Crandall has been walking along the rivers in the Methow watershed – the Methow, Chewuch and Twisp – with an elongated thermometer, taking the water temperature as he goes.

Crandall isn’t wandering at random. He’s following color-coded maps based on thermal imagery taken with an infrared camera from helicopter flights in 2009. The maps show all three rivers, small streams and tributaries, which are shaded from gold to hot pink, to purple, blue and black. Gold areas are the warmest, purple and blue are cold, and black is the coldest.

“It’s just like being a pirate going out to find treasure. The 2009 flight data are my map,” Crandall said.

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